1. Field of the Invention
The present invention relates to a safety protective device, and more particularly to a safety protective device for a working machine, such as a drilling machine or the like.
2. Description of the Related Art
A conventional working machine, such as a drilling machine 1, in accordance with the prior art shown in FIGS. 9 and 10 comprises a blade seat 11 movable relative to a sheet plate 2 and having a bottom face provided with a plurality of blades 12 to move therewith, and a protective cover 13 mounted on the blade seat 11 to cover the blades 12 of the blade seat 11. The protective cover 13 is formed with two elongated slots 131, and the blade seat 11 is provided with two limit posts 111 each slidably mounted in a respective one of the two elongated slots 131, so that the protective cover 13 is movable relative to the blade seat 11.
However, when the bottom edge 132 of the protective cover 13 is rested on the sheet plate 2, one side of the bottom edge 132 of the protective cover 13 is pushed upward by the sheet plate 2 and the other side of the bottom edge 132 of the protective cover 13 is not stopped by the sheet plate 2 and is moved downward by movement of the protective cover 13, so that the protective cover 13 is deflected and the elongated slots 131 of the protective cover 13 are interlocked with the limit posts 111 of the blade seat 11, thereby affecting movement of the blade seat 11 due to deflection of the protective cover 13.